Should I be on my crutches?

I am 14 years old and on Saturday I sprained my knee skiing. I felt alot of pain(I grabbed my knee) but it went away a little so I continued to ski.(I felt a pop when it happened so that probably wasn't the best idea)Well we finnaly left and when I took my boot off I put on my shoe and than I put my snow boots on. I was limping alot and by the end of the night if I moved my knee at all I got extreme pain. My knee felt better the next day but I went to the urgent care anyway. they gave me a brace and gave me crutches, but I didn't use them(they hurt so bad) anyway I went to school and have been sitting out in gym. but my knee has been the same for the past 3 days, it's not worse nor better. My other knee is starting to bother me because I have been limping around and it is starting to pop out at random times. it is still tender when you touch it though/put pressure on the right side. I havn't used the crutches for the past 3 days so I'm worried that I could be hurting it worse.

or I could be hurting my other knee. My problem is I told my gym teacher that It feels a little better, and I havn't used the crutches in 3 days so wouldn't it look bad/weird if I came in on crutches after not using them for so many days. also since I told my teacher it was feeling better don't you think that may seem hypocritical even though I'm not trying to be. I'm thinking of saying it's still bothering me and I think if I take a day off of it, it may help make it feel better
or
My parents want me to see if It gets better after staying off of it for a day.

do you think that I should use them.

btw it's not swollen, but the doctor said that I may have torn something, and my other knee hurts when I bend it up, and it is tender in the front, but it doesn't hurt as a sprain, it just feels as if it's been overused

Yes you need to use the crutches. The reason you were given them is so that your injured leg doesn't bear weight and it can heal. With you walking on it, it's not going to heal. Instead what's happening is your other leg is compensating and that will get tired and sore too. The crutches will rest your knee and give your other leg the support it needs to keep you upright.